Developing landscape habitat models for rare amphibians with small geographic ranges: a case study of Siskiyou Mountains salamanders in the western USA

To advance the development of conservation planning for rare species with small geographic ranges, we determined habitat associations of Siskiyou Mountains salamanders (Plethodon stormi) and developed habitat suitability models at fine (10 ha), medium (40 ha), and broad (202 ha) spatial scales using available Geographic Information Systems data and logistic regression analysis with an information theoretic approach. Across spatial scales, there was very little support for models with structural habitat features, such as tree canopy cover and conifer diameter. Model-averaged 95% confidence intervals for regression coefficients and associated odds ratios indicated that the occurrence of Siskiyou Mountains salamanders was positively associated with rocky soils and Pacific madrone (Abutus menziesii) and negatively associated with elevation and white fir (Abies concolor); these associations were consistent across 3 spatial scales. The occurrence of this species also was positively associated with hardwood density at the medium spatial scale. Odds ratios projected that a 10% decrease in white fir abundance would increase the odds of salamander occurrence 3.02–4.47 times, depending on spatial scale. We selected the model with rocky soils, white fir, and Oregon white oak (Quercus garryana) as the best model across 3 spatial scales and created habitat suitability maps for Siskiyou Mountains salamanders by projecting habitat suitability scores across the landscape. Our habitat suitability models and maps are applicable to selection of priority conservation areas for Siskiyou Mountains salamanders, and our approach can be easily adapted to conservation of other rare species in any geographical location.     

阿拉善马鹿(Cervus alashanicus)生境适宜性评价

阿拉善马鹿(Cervus alashanicus)目前仅分布于贺兰山地区,对该物种进行生境适宜性的评价和分析是物种有效保护的前提和基础。2013—2014年通过样线调查及巡山资料查询,确定阿拉善马鹿出现位点86个,结合13种环境变量数据,利用最大熵(maximum entropy,MaxEnt)模型,并根据最大约登指数划定适宜与不适宜生境区,对贺兰山地区阿拉善马鹿的生境适宜性进行评价。ROC曲线(receiver operating characteristic curve)检测证明模型预测精度较高,研究结果表明:阿拉善马鹿主要分布于贺兰山东坡的中部和南部,以及西坡的中北部,适宜生境面积为667.87 km~2,占研究区域面积的18.2%;矿区、坡度和海拔是影响阿拉善马鹿分布的最主要环境变量,矿区对阿拉善马鹿的影响最大,建议管理部门加大对此人为干扰的管控力度,控制和减少现有矿区的规模,以促进该种群的发展。     

Finding fishers: determining fisher occupancy in the Northern Rocky Mountains

Monitoring rare and elusive carnivores is inherently challenging because they often occur at low densities and require more resources to effectively assess status and trend. The fisher (Pekania pennanti) is an elusive mesocarnivore endemic to North America; in its western populations it is classified as a species of greatest conservation need. During winter of 2018–2019, we deployed remotely triggered cameras in randomly selected, spatially balanced 7.5-km × 7.5-km grid cells across a broad study area in western Montana, Idaho, and eastern Washington, USA. As part of this large-scale, multi-state monitoring effort, we conducted an occupancy assessment of the Northern Rocky Mountain fisher population at a range-wide scale. We used non-spatial occupancy models to determine the current extent of fisher occurrence in the Northern Rocky Mountains and to provide baseline occupancy estimates across a broad study area and a refined sampling frame for future monitoring. We used a spatial occupancy model to determine patterns in fisher occurrence across their Northern Rocky Mountain range while explicitly correcting for spatially induced overdispersion. Additionally, we assessed factors that influenced fisher occurrence through covariate occupancy modeling that considered predicted fisher habitat, site-level environmental characteristics, and the influence of available harvest records (incidental and regulated). We detected fishers in 32 out of 318 (10%) of our surveyed cells, and estimated that overall, 160 (14%; 95% CI = 115–218) of 1,143 grid cells were occupied by fishers. Fisher occupancy was positively associated with our stratum that contained cells with a greater proportion of predicted fisher habitat and with proximity to nearest 2000–2015 harvest location. Fisher occupancy was weakly and positively associated with increased canopy cover. Our spatial model identified 2 areas with higher predicted occupancy: a large area across the Idaho Nez Perce-Clearwater National Forest, and a smaller area in the Cabinet Mountain Range crossing the northern border of Idaho and Montana. We used spatial occupancy results from our original sampling frame to create a biologically derived refined sampling frame for future monitoring. Within the bounds of our refined sampling frame, we estimated that 155 (22%; 95% CI = 110–209) of 700 grid cells were occupied by fishers. By incorporating our increasing understanding of fisher habitat with contemporary analytical techniques, we defined current range-wide occupancy of the Northern Rocky Mountain fisher population, identified core areas of fisher occurrence for future conservation efforts, and used our model results to create a refined sampling frame for future fisher monitoring in the Northern Rocky Mountains.     

Habitat preferences of cattail species and hybrids (Typha spp.) in eastern Canada

Interspecific hybridization is widespread in plants and is an important evolutionary process. Hybrids may be fitter than their parental species, at least under some environmental conditions, and this may lead to partitioning of taxa by habitat. In eastern Canada, two cattail species (Typha latifolia and Typha angustifolia) and their hybrid (Typha x glauca) are known to have become increasingly widespread in recent decades, although their habitat preferences and patterns of co-existence at the local scale are not well known. We quantified the occurrence of these three taxa in three different habitat types (high traffic, low traffic, and ‘natural’) at 40 different sites along a sampling route of approximately 2000 km in eastern Canada. There were no significant overall associations between habitat type and taxon, although intraspecific comparisons among sites showed that the hybrid was most likely to grow in high traffic (highly disturbed) sites. In addition, pairwise comparisons revealed significant independence of T. latifolia and T. angustifolia, although the hybrid was equally likely to co-exist with either of its parental species. The presence of the three taxa in several habitats, including highly disturbed roadside areas, is consistent with their increasingly invasive tendencies.     

Spatial interactions between grey wolves and Eurasian lynx in Białowieża Primeval Forest, Poland

Various species of large predators are reported to influence each other through interference or exploitation competition that may affect demography and survival of the subordinate species. We analyzed spatial relationships between grey wolf (Canis lupus) and Eurasian lynx (Lynx lynx) in Białowieża Primeval Forest (BPF, eastern Poland) to determine how they partitioned the space. The wolves (n = 8) and lynx (n = 14) were radio-tracked in 1991–1999. Three wolves and seven lynx were radio-tracked simultaneously in 1994–1996. Territories of wolf packs and home ranges of lynx overlapped considerably (76% of wolf territories and 50% of lynx home ranges, on average). In three cases, their core areas were also overlapping. Wolf-lynx dyads with overlapping home ranges were simultaneously located at distances from 0 to 28 km from each other. We found neither avoidance nor attraction between wolves and lynx occupying the same areas. We concluded that in BPF, the two large predators coexist due to specialization on different preferred prey and heterogeneous habitat.     

<Emphasis Type="Italic">Myrmica</Emphasis> host-ants limit the density of the ant-predatory large blue <Emphasis Type="Italic">Maculinea nausithous</Emphasis>

Butterflies of the highly endangered genus Maculinea are parasites of red Myrmica ants. Prior to the adoption by Myrmica worker ants Maculinea caterpillars feed on a specific host plant. This field study aims to answer the question whether the density and distribution of the host plant Sanguisorba officinalis or the density of the host ant M. rubra limit the density of M. nausithous egg, larval and adult stage. We found that the density of M. nausithous egg stage and adult stage increased with the density of the host ant. The density of M. nausithous caterpillars was not associated with ant density or plant density. This study suggests that the density of M. nausithous is limited by the density of the host ant M. rubra. We conclude that habitat management for M. nausithous should focus on the maintenance of habitats that hold both resources, but that enable high densities of M. rubra. In addition, it is discussed why high densities of host ants might be more important in predatory than in cuckoo-feeding Maculinea.     

Evolutionary history of the scorpionfly Dicerapanorpa magna (Mecoptera,Panorpidae)

Climate changes can have fundamental impacts on the distributional patterns of montane species, and range shifts frequently lead to allopatric divergence followed by the establishment of secondary contact zones. Many European and North American organisms have retreated to southern refugia during glacial periods and colonized northward during postglacial periods, but little is known about the evolutionary response of cold‐adapted insects to Pleistocene climate changes in eastern Asia. The scorpionfly Dicerapanorpa magna (Chou), with cold temperate habitat preference and weak dispersal ability, provides a good model system to explore how climate changes have influenced the distribution and divergence of cold‐adapted insects in eastern Asia. This study reconstructed the demographic dynamics and evolutionary history of D. magna with phylogeographic approaches, and predicted the species’ suitable areas under the Last Glacial Maximum (LGM) and current scenarios with the ecological niche modelling analysis. The mitochondrial cytochrome c oxidase subunit I resolved three phylogenetic lineages in D. magna dating back to Pleistocene, corresponding well with the geographically isolated Qinling, Bashan and Minshan Mountains. The ecological niche modelling recovered the suitable habitats for D. magna were the Qinling and Bashan Mountains under LGM and current conditions. The three lineages of D. magna might be in a process of incipient speciation, and likely derived their current distribution from separate glacial origins, followed by vicariance and divergence.     

Tandem repeat markers for population genetic studies of the protected California tiger salamander (<Emphasis Type="Italic">Ambystoma californiense</Emphasis>)

Habitat loss is the single greatest threat to persistence of the critically threatened California tiger salamander (Ambystoma californiense). To aid management plans that designate critical habitat for this species, I developed and characterized 21 tetranucleotide microsatellite markers using two native populations in Santa Barbara and Alameda Counties. Allelic variation and average heterozygosities were lower in the endangered Santa Barbara population (allele range 1–4, mean 2.4; H _O = 0.308 H _E = 0.288) compared with the threatened Alameda population (allele range 2–10, mean 6.7; H _O = 0.712, H _E = 0.722). In-depth population studies using these markers will provide vital information for plans to assign critical habitat that optimize gene flow among breeding populations, as well as for identifying non-native hybrid genotypes that threaten native A. californiense stocks. Beyond the conservation goals for A. californiense, the close phylogenetic relationships within the tiger salamander complex also suggest a broad utility for population studies using these markers.     

Mapping potential habitats of threatened plant species in a moist tall grassland using hyperspectral imagery

We examined the capability of hyperspectral imagery to map habitat types of under-storey plants in a moist tall grassland dominated by Phragmites australis and Miscanthus sacchariflorus, using hyperspectral remotely-sensed shoot densities of the two grasses. Our procedure (1) grouped the species using multivariate analysis and discriminated habitat types (species groups) based on P. australis and M. sacchariflorus shoot densities, (2) used estimated shoot densities from hyperspectral data to draw a habitat type map, and (3) analyzed the association of threatened species with habitat types. Our identification of four habitat types, using cluster analysis of the vegetation survey coverage data, was based on P. australis and M. sacchariflorus shoot density ratios and had an overall accuracy of 77.1% (kappa coefficient = 0.71). Linear regression models based on hyperspectral imagery band data had good accuracy in estimating P. australis and M. sacchariflorus shoot densities (adjusted R ² = 0.686 and 0.708, respectively). These results enabled us to map under-storey plant habitat types to an approximate prediction accuracy of 0.537. Among the eight threatened species we examined, four exhibited a significantly biased distribution among habitat types, indicating species-specific habitat use. These results suggest that this procedure can provide useful information on the status of potential habitats of threatened species.     

The evolutionary consequences of habitat fragmentation: Body morphology and coloration differentiation among brook trout populations of varying size

A reduction in population size due to habitat fragmentation can alter the relative roles of different evolutionary mechanisms in phenotypic trait differentiation. While deterministic (selection) and stochastic (genetic drift) mechanisms are expected to affect trait evolution, genetic drift may be more important than selection in small populations. We examined relationships between mature adult traits and ecological (abiotic and biotic) variables among 14 populations of brook trout. These naturally fragmented populations have shared ancestry but currently exhibit considerable variability in habitat characteristics and population size (49 < N_c < 10,032; 3 < N_b < 567). Body size, shape, and coloration differed among populations, with a tendency for more variation among small populations in both trait means and CV when compared to large populations. Phenotypic differences were more frequently and directly linked to habitat variation or operational sex ratio than to population size, suggesting that selection may overcome genetic drift at small population size. Phenotype–environment associations were also stronger in females than males, suggesting that natural selection due to abiotic conditions may act more strongly on females than males. Our results suggest that natural and sexual‐selective pressures on phenotypic traits change during the process of habitat fragmentation, and that these changes are largely contingent upon existing habitat conditions within isolated fragments. Our study provides an improved understanding of the ecological and evolutionary consequences of habitat fragmentation and lends insight into the ability of some small populations to respond to selection and environmental change.     

罗霄山脉中段地区银木荷群落研究

为充实罗霄山脉地区的植被类型研究,探讨银木荷群落与海拔和纬度的关系,该文采用群落学研究方法,调查了罗霄山脉中段井冈山、齐云山、南风面和五指峰4处典型的银木荷群落。结果表明:(1)4个群落分别有维管植物30科50属84种、45科70属106种、33科47属78种和38科66属99种。(2)银木荷在井冈山和齐云山中均为优势种,其重要值在群落中最高; 在南风面和五指峰中为次优势种。(3)井冈山、齐云山和五指峰的银木荷群落物种丰富度高,且分布均匀。南风面的银木荷群落物种丰富度偏低,且分布不甚均匀。(4)4个群落中银木荷所处的演替阶段不同,井冈山和齐云山种群为从稳定型向衰退型的过渡,南风面种群处于衰退型,五指峰种群经历一段时间的衰退后,可重新侵入到群落中。(5)4个群落的高位芽植物均高于总种数的75%,地下芽植物和地面芽植物为其次。4个银木荷群落可分为2类:第1类是南风面群落,以猴头杜鹃(Rhododendron simiarum)林的特点为主; 第2类是井冈山、齐云山和五指峰群落,其群落种类丰富,生物多样性高,以热带性属为主,物种数量随海拔增高而减少,随纬度升高而减少。银木荷群落是中亚热带常绿阔叶林的典型代表,不同演替阶段银木荷群落同时存在是罗霄山脉中段地区作为植物栖息地的又一明证。     

Modeling ecological minimum requirements for distribution of greater sage‐grouse leks: implications for population connectivity across their western range,U.S.A

Greater sage‐grouse Centrocercus urophasianus (Bonaparte) currently occupy approximately half of their historical distribution across western North America. Sage‐grouse are a candidate for endangered species listing due to habitat and population fragmentation coupled with inadequate regulation to control development in critical areas. Conservation planning would benefit from accurate maps delineating required habitats and movement corridors. However, developing a species distribution model that incorporates the diversity of habitats used by sage‐grouse across their widespread distribution has statistical and logistical challenges. We first identified the ecological minimums limiting sage‐grouse, mapped similarity to the multivariate set of minimums, and delineated connectivity across a 920,000 km² region. We partitioned a Mahalanobis D² model of habitat use into k separate additive components each representing independent combinations of species–habitat relationships to identify the ecological minimums required by sage‐grouse. We constructed the model from abiotic, land cover, and anthropogenic variables measured at leks (breeding) and surrounding areas within 5 km. We evaluated model partitions using a random subset of leks and historic locations and selected D² (k = 10) for mapping a habitat similarity index (HSI). Finally, we delineated connectivity by converting the mapped HSI to a resistance surface. Sage‐grouse required sagebrush‐dominated landscapes containing minimal levels of human land use. Sage‐grouse used relatively arid regions characterized by shallow slopes, even terrain, and low amounts of forest, grassland, and agriculture in the surrounding landscape. Most populations were interconnected although several outlying populations were isolated because of distance or lack of habitat corridors for exchange. Land management agencies currently are revising land‐use plans and designating critical habitat to conserve sage‐grouse and avoid endangered species listing. Our results identifying attributes important for delineating habitats or modeling connectivity will facilitate conservation and management of landscapes important for supporting current and future sage‐grouse populations.     

Marine reserves indirectly affect fine‐scale habitat associations,but not overall densities,of small benthic fishes

Many large, fishery‐targeted predatory species have attained very high relative densities as a direct result of protection by no‐take marine reserves. Indirect effects, via interactions with targeted species, may also occur for species that are not themselves targeted by fishing. In some temperate rocky reef ecosystems, indirect effects have caused profound changes in community structure, notably the restoration of predator–urchin–macroalgae trophic cascades. Yet, indirect effects on small benthic reef fishes remain poorly understood, perhaps because of behavioral associations with complex, refuge‐providing habitats. Few, if any, studies have evaluated any potential effects of marine reserves on habitat associations in small benthic fishes. We surveyed densities of small benthic fishes, including some endemic species of triplefin (Tripterygiidae), along with fine‐scale habitat features in kelp forests on rocky reefs in and around multiple marine reserves in northern New Zealand over 3 years. Bayesian generalized linear mixed models were used to evaluate evidence for (1) main effects of marine reserve protection, (2) associations with habitat gradients, including complexity, and (3) differences in habitat associations inside versus outside reserves. No evidence of overall main effects of marine reserves on species richness or densities of fishes was found. Both richness and densities showed strong associations with gradients in habitat features, particularly habitat complexity. In addition, some species exhibited reserve‐by‐habitat interactions, having different associations with habitat gradients inside versus outside marine reserves. Two species (Ruanoho whero and Forsterygion flavonigrum) showed stronger positive associations with habitat complexity inside reserves. These results are consistent with the presence of a behavioral risk effect, whereby prey fishes are more strongly attracted to habitats that provide refuge from predation in areas where predators are more abundant. This work highlights the importance of habitat structure and the potential for fishing to affect behavioral interactions and the interspecific dynamic attributes of community structure beyond simple predator–prey consumption and archetypal trophic cascades.     

Non‐native salmonids affect amphibian occupancy at multiple spatial scales

Aim The introduction of non‐native species into aquatic environments has been linked with local extinctions and altered distributions of native species. We investigated the effect of non‐native salmonids on the occupancy of two native amphibians, the long‐toed salamander (Ambystoma macrodactylum) and Columbia spotted frog (Rana luteiventris), across three spatial scales: water bodies, small catchments and large catchments. Location Mountain lakes at ≥ 1500 m elevation were surveyed across the northern Rocky Mountains, USA. Methods We surveyed 2267 water bodies for amphibian occupancy (based on evidence of reproduction) and fish presence between 1986 and 2002 and modelled the probability of amphibian occupancy at each spatial scale in relation to habitat availability and quality and fish presence. Results After accounting for habitat features, we estimated that A. macrodactylum was 2.3 times more likely to breed in fishless water bodies than in water bodies with fish. Ambystoma macrodactylum also was more likely to occupy small catchments where none of the water bodies contained fish than in catchments where at least one water body contained fish. However, the probability of salamander occupancy in small catchments was also influenced by habitat availability (i.e. the number of water bodies within a catchment) and suitability of remaining fishless water bodies. We found no relationship between fish presence and salamander occupancy at the large‐catchment scale, probably because of increased habitat availability. In contrast to A. macrodactylum, we found no relationship between fish presence and R. luteiventris occupancy at any scale. Main conclusions Our results suggest that the negative effects of non‐native salmonids can extend beyond the boundaries of individual water bodies and increase A. macrodactylum extinction risk at landscape scales. We suspect that niche overlap between non‐native fish and A. macrodactylum at higher elevations in the northern Rocky Mountains may lead to extinction in catchments with limited suitable habitat.     

Reproductive isolation and cryptic introgression in a sky island enclave of Appalachian birds

Reproductive isolation is central to the speciation process, and cases where the strength of reproductive isolation varies geographically can inform our understanding of speciation mechanisms. Although generally treated as separate species, Black‐capped chickadees (Poecile atricapillus) and Carolina chickadees (P. carolinensis) hybridize and undergo genetic introgression in many areas where they come into contact across the eastern United States and in the northern Appalachian Mountains. The Great Smoky Mountains harbor the last large breeding population of atricapillus in the southern Appalachians, isolated from the species’ main range by nearly 200 km. This population is believed to be reproductively isolated from local carolinensis due to an unusual, behaviorally mediated elevational range gap, which forms during the breeding season and may function as an incipient reproductive isolating mechanism. We examined the effectiveness of this putative isolating mechanism by looking for genetic introgression from carolinensis in Great Smoky Mountain atricapillus. We characterized this population and parental controls genetically using hundreds of amplified fragment length polymorphism (AFLP) loci as well as mitochondrial DNA (mtDNA) sequence data from cytochrome‐b. Great Smoky Mountain atricapillus have experienced nuclear genetic introgression from carolinensis, but at much lower levels than other populations near the hybrid zone to the north. No mitochondrial introgression was detected, in contrast to northern contact areas. Thus, the seasonal elevational range gap appears to have been effective in reducing gene flow between these closely related taxa.     

Effects of structural heterogeneity provided by the floating macrophyte <Emphasis Type="Italic">Eichhornia azurea</Emphasis> on the predation efficiency and habitat use of the small Neotropical fish <Emphasis Type="Italic">Moenkhausia sanctaefilomenae</Emphasis>

Macrophytes have a fundamental structuring role in aquatic environments. Several authors have suggested that trophic interactions are particularly mediated by aquatic plants. In the current article, we evaluated the effects of the structural heterogeneity provided by Eichhornia azurea (Kunth) roots on predation and habitat use by the small fish Moenkhausia sanctaefilomenae (Steindachner). We tested the hypotheses that (i) high structural heterogeneity protects macroinvertebrates against predation by M. sanctaefilomenae; (ii) distinct prey types are differently protected by the refuge provided by roots; and (iii) the behavior of M. sanctaefilomenae is affected by the structural heterogeneity provided by macrophyte roots. To test these hypotheses, we performed an experiment in 20 l aquaria in which macroinvertebrates (Cypricercus sp. and Chironomus sp.) were exposed to M. sanctaefilomenae predation for 4 h under three structural heterogeneities, represented by different root densities. High structural heterogeneity protected macroinvertebrates against predation. Additionally, E. azurea roots similarly protected different prey species. The macrophyte spatial structure substantially changed the habitat use of M. sanctaefilomenae. In general, our results corroborated the hypothesis that the structural heterogeneity provided by E. azurea roots significantly affects predation and habitat use by M. sanctaefilomenae. Handling editor: S. Declerck     

Assessing the genetic consequences of habitat fragmentation on the federally threatened cheat mountain salamander (Plethodon nettingi): a comparative,multi-locus approach

Comparative population genetic studies of closely related taxa provide a powerful framework for evaluating if and to what degree a species of conservation concern has been negatively impacted by factors such as habitat fragmentation, decreased population connectivity, inbreeding and genetic drift. In this study, we take advantage of a paired sampling strategy to compare the population genetics of the geographically restricted, federally threatened Cheat Mountain salamander (Plethodon nettingi) to those of its partially sympatric, but much more widely distributed congener, the red-backed salamander (P. cinereus), where the two species overlap in the Appalachian mountains of West Virginia. Mitochondrial DNA haplotype and nucleotide diversity were lower in P. nettingi, as were a variety of metrics of nuclear genetic diversity estimated from microsatellite data. Population differentiation and structuring were greater in P. nettingi, suggesting reduced gene flow following fragmentation. Significant inbreeding and evidence of recent population bottlenecks were also seen in P. nettingi and estimated population sizes were smaller. Estimates of contemporary gene flow, as measured through kinship, also showed more restricted gene flow in P. nettingi. Overall, our comparative study provides strong evidence that the small and highly fragmented nature of its geographic distribution has resulted in a suite of negative genetic consequences for the federally threatened Cheat Mountain salamander. Management efforts aimed at enhancing the genetic health and long-term viability of this species should focus on increasing population connectivity through establishment of forest habitat corridors where possible and exploring the potential merits of translocations.

     

Ecological niche conservation and differentiation in the wood-feeding cockroaches, Cryptocercus, in the United States

The distribution of a species is determined by a set of ecological correlates (biotic and abiotic factors) and historical phenomena that define and constrain its ecological niche. By examining the geographical projection of the ecological niche, it is possible to identify areas that are suitable for the species ecologically but that are not actually inhabited. Previous studies have used such discords to anticipate the existence of undescribed species; the absence of species may also result from historical barriers that have prevented colonization of the area. Thus, discords between potential and realized niches of a species may result from aspects of the species’s biology (e.g. lack of dispersal ability, specific habitat requirements) or from barriers to dispersal. In this study, we developed ecological niche models of the five Nearctic species of wood‐feeding cockroaches in the genus Cryptocercus. One species, C. clevelandi, occurs in the western USA and four (C. darwini, C. garciai, C. punctulatus, C. wrighti) are distributed in the Appalachian Mountains in the eastern USA. In general, modelled niches for all species showed ecological restriction relative to the total range of available conditions. Niche models for the eastern USA species predicted the geographical distributions of the other eastern USA species, with the exception of C. garciai, suggesting general overall conservatism in ecological characteristics. Some interspecific differences in modelled niches were also apparent. In general, C. clevelandi was predicted to occupy cooler and drier areas relative to the eastern USA species; among the eastern USA species, C. darwini and C. garciai were predicted to inhabit warmer areas relative to C. punctulatus and C. wrighti. Interspecific differences and similarities were consistent with the phylogenetic relationships among Cryptocercus species previously reported. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90 , 457–466.     

Predicting changes in the abundance of African wetland birds by incorporating abundance–occupancy relationships into habitat association models

Aim To map changes in the abundance of African wetland birds using remotely derived habitat data. We show that abundance–occupancy relationships can be coupled with habitat association models to map changes in abundance. As conservation resources are more easily allocated when spatial and temporal patterns of abundance are known, our method provides guidance for conservation planning. Location Papyrus, Cyperus papyrus, swamps in east central Africa. Methods Presence/absence surveys of six bird species in 93 wetlands were used to construct models predicting probability of occurrence from habitat characteristics. Densities were then determined from surveys in 23 additional wetlands and modelled as functions of occurrence probability. We then used satellite imagery to derive habitat characteristics remotely in two time periods (1984–87 and 2000–03) and used the modelled relationships between (1) habitat and occupancy and (2) occupancy and density, to infer changes in abundance in all c. 30,000 wetlands within the study area. Results Wetlands within the region declined by 8.6% between the two time periods, but by > 75% in regions of high human population density. Bird densities were also highest in these regions, which comprised wetlands subject to high levels of disturbance. The geographical coincidence of high densities and habitat loss and the existence of positive associations between bird density and occurrence meant that birds declined by much more than the average rate of their habitat. Main conclusions Targeting conservation efforts in areas with high drainage would protect a high proportion of the bird populations. Encouraging people to derive income from disturbance to which the birds are tolerant, rather than drainage, is likely to be an effective strategy. Because habitat characteristics are a key driver of abundance–occupancy relationships, we conclude that there is wide‐scale scope to couple abundance–occupancy relationships with remote habitat mapping to efficiently inform conservation planning.     

Distribution,movement, and microhabitat use of the introduced predatory snail Euglandina rosea in Hawaii: implications for management

The purposeful introduction of the land snail Euglandina rosea, which feeds exclusively on snails and slugs, has been implicated as a major factor in the decline of diverse Pacific island land snail faunas. We report on the distribution, movement patterns, and microhabitat preferences of E. rosea in a gulch in the Waianae Mountains, Oahu, Hawaii, because such data will help focus management actions at a local scale to protect native snail populations in areas where E. rosea is established. The Waianae Mountains harbor many endangered or threatened snails, most currently found in isolated habitat patches near the ridges. Conversely, most living individuals (28/29) and shells (46/56) of E. rosea were collected within the gulch, which supported higher densities of other native and non‐native snails, and was cooler and more moist than the ridges. Thirteen individuals of E. rosea were tracked (eight directly using a bobbin and thread method, and five indirectly by mark–recapture); most (10/13) moved on average <2.5 m per week (range 0.1–25.21 m), and all stayed within the gulch. Members of E. rosea preferred leaf litter over open, fern/shrub, or wood microhabitats. There were large differences in the population density of E. rosea over small spatial scales, indicating that there may be places where native snail populations could persist even in areas where populations of E. rosea are established. Identifying areas with differing population densities of E. rosea is critical for not only understanding why some native snail species may be more vulnerable to extinction, but also to locate areas where predation pressure is low and conservation efforts will be most likely to succeed.